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1.
通过盆栽实验的方法,研究了三种秸秆有机肥对次生盐渍化土壤的EC值、硝酸根离子含量和油菜生物量的影响。结果表明,M1有机肥显著增加油菜的生物量,但在一定程度上增加土壤盐分含量;M2有机肥的效果与M1有机肥效果趋势相似,但增加土壤中的盐分含量的程度要小的多;而施用秸秆肥料M3,在增加油菜生物量的同时显著降低土壤盐分含量,减轻了土壤的次生盐渍化程度。结果表明,三种秸秆有机肥均能提高油菜对盐渍化的耐受能力,增加其生物量。采用M3秸秆有机肥改良土壤盐渍化是一条有效途径,但其最佳施用量与土壤盐渍化程度有关,非盐渍化土壤施用过多M3肥料将降低生物量。 相似文献
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在宁夏引黄灌区灌淤土设置田间试验,研究不同水氮措施对芹菜-白菜轮作体系中的氮素利用与平衡的影响,结果表明:节水灌溉的W2N3(推荐施氮)处理与传统灌溉(W1N3)(推荐施氮)的处理相比,芹菜的产量、吸氮量分别高12.2%、14.7%,白菜的产量、吸氮量分别高22.4%、4.4%。在氮素平衡方面,推荐施氮处理氮素损失比传统施氮损失分别低53kghm-2(传统灌溉)、30kghm-2(节水灌溉)。节水条件下推荐施氮处理的土壤剖面上的无机氮残留浓度,减少量分别达到3~13kghm-2。节水灌溉下与传统灌溉相比,节水灌溉的土壤残留硝态氮的含量均比传统灌溉低,而且主要分布在0~60cm表层,推荐施氮量的土壤残留硝态氮的含量又比习惯施氮量低。 相似文献
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本文对甘肃景电灌区次生盐化土壤的理化性质进行了研究 .该区次生盐渍化土壤主要为硫酸盐氯化物和氯化物硫酸盐型 ,水溶性钠离子在阳离子中占绝对优势 .土壤通体碳酸钙含量很高 ,并有少量的石膏 .钠离子饱和度很高 ,具有钠质特性或钠质化现象 ,盐化与钠质化同时进行 .在此基础上对次生盐渍化的机理和改良进行了讨论 相似文献
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针对保护地渗灌存在的问题 ,研制了高效节水、经济耐用、性能优良的节点式渗灌管。试验结果表明 ,此种渗灌管节水效率是普通渗灌管的一倍以上 ,生产番茄的灌溉定额为 12 2 5 5~ 12 90m3 hm- 2 ,植株间番茄果实的均匀度达到了0 .75以上 ,单位面积产量 58680~ 59910kghm- 2 ,水资源的效率为 46.44~ 47.88kgm- 3 。 相似文献
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从作物高产、优质以及节水,特别是防治土壤退化的角度,提出了水分是保护地生产中最为活跃和重要的因子,水分调控对保护地土壤退化有很多方面的影响;阐述了保护地生产中土壤水分管理的重要性;介绍了近年来保护地灌溉研究取得的一些成果;在此基础上讨论了今后保护地土壤水分管理的研究重点应包括:主要栽培作物种类及品种的需水规律、土壤盐分积累特点和水分运动规律、水肥耦合效应原理及其技术等. 相似文献
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我国是水资源比较丰富,总量位居世界前列,但是人均占有量却远远低于世界平均水平.从某种程度来说我国水资源比较匮乏.当前,灌溉系统自动化的水平较低已经成为了我国农业水资源高效利用的绊脚石.[1]在以色列、日本、美国这些发达国家地区,自动化灌溉已经得到了普及.在传感器的帮助下,水灌溉已经由传统的充分灌溉过渡到非充分灌溉,传感器不仅可以检测土壤水含量,还可以监测土壤的墒情和农作物的生长,真正做水资源的智能化控制.要想发展农业现代化就必须提高水资源利用率,实现高效农业和精细农业.仅凭一项节水灌溉是无法实现农业现代化,还应当考虑到水资源的开发、输送、灌溉技术等,这些方面都会应当到对水资源的合理利用. 相似文献
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井渠结合具有提高灌溉水资源利用率和调控地下水双重作用.探讨了对井渠结合灌区灌溉水利用系数、灌区适宜的渠井用水比例、水资源开发利用中的节水与养水、以及灌区用水管理等问题. 相似文献
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S. Shaw 《Journal of Computer Assisted Learning》1993,9(2):93-99
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained. 相似文献
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European Community policy and the market 总被引:1,自引:0,他引:1
C. Lloyd 《Journal of Computer Assisted Learning》1993,9(2):86-91
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven. 相似文献
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融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。 相似文献
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Wayne O’Brien Author Vitae 《Journal of Systems and Software》2008,81(11):1997-2013
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them. 相似文献
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This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives. 相似文献
16.
Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what
is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic
sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and
its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of
an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify
robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can
or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
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David Poole 《Computational Intelligence》1989,5(2):97-110
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given. 相似文献
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Watts S. Humphrey 《Annals of Software Engineering》2002,14(1-4):39-72
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical. 相似文献
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基于复小波噪声方差显著修正的SAR图像去噪 总被引:4,自引:1,他引:3
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。 相似文献